A three-parameter single-step time integration method for structural dynamic analysis

The existing three-parameter single-step time integration methods, such as the Generalized-a method, improve numerical dissipation by modifying equilibrium equation at time points, which cause them to lose accuracy due to the interpolation of load vectors. Moreover, these three-parameter methods do not present an available formulation applied to a general secondorder non linear differential equatio n. To solve these problems, this paper proposes an innovative three-parameter single-step method by introducing an additional variable into update equations. Although the present method is spectrally identical to the Generalized-cx method for undamped systems, it possesses higher accuracy since it strictly satisfies the equilibrium equation at time points, and can be readily used to solve nonlinear equations. By the analysis of accuracy, stability, numerical dissipation and dispersion, the optimal second-order implicit and explicit schemes are generated, which can maximize low-frequency accuracy when high-frequency dissipation is specified. To check the performance of the proposed method, several numerical experiments are conducted and the proposed method is compared with a few up-to-date methods.

Single-step transepithelial photorefractive keratectomy in high myopia：qualitative and quantitative visual functions

AIM：To investigate quantitative and qualitative optical outcomes of single-step transepithelial photorefractive keratectomy（Trans PRK）in high myopia.METHODS：In a prospective interventional case-series,30 eyes with high myopia（-6.00 to-8.75 D）with（up to-3.00 D）or without astigmatism were enrolled from Bina Eye Hospital,Tehran,Iran. One-step Trans PRK was performed with aberration-free aspherical optimized profile and SCHWIND AMARIS 500 laser. One-year follow-up results for refraction,visual acuities,vector analysis,ocular wavefront（OWF）and corneal wave-front（CWF）higher order aberrations（HOA）,contrast sensitivity（CS）,and postoperative haze were assessed.RESULTS：After the surgery,both photopic and mesopic CSs significantly improved（both P〈0.001）. We detected significant induction of OWF coma and trefoil（P〈0.001 for both）HOAs; CWF coma（P=0.002）,spherical（P〈0.001）,and tetrafoil（P=0.003）HOAs in 6 mm analysis diameter; and CWF trefoil（P=0.04）HOA in 4 mm analysis diameter. The range of mean induction observed for various HOAs was0.005-0.11 μm. The 86.7% of eyes reached an uncorrected distance visual acuity of 20/20 or better; 96.7% of eyes were within ±0.5 D of targeted spherical refraction. In vector analysis,mean correction index value was 1.03 and mean index of success was 0.22. By 12mo after the operation,no eye lost any number of corrected distancevisual acuity lines. We detected no corneal haze greater than 1~＋ throughout the follow-up.CONCLUSION：Our findings show promising effects of single-step Trans PRK on quality of vision in high myopic eyes. It also improves refraction and visual acuity.

Single-step thermal carburization synthesis of supported molybdenum carbides from molybdenum-containing methyl-silica

A novel synthesis route to obtain highly dispersed molybdenum carbides in porous silica is described. The synthesis was carried out by a single-step heat treatment of molybdenum-containing and methyl-modified silica （Mo-M-SiO2） in argon atmosphere at 973 K. Mo-M-SiO2 precursor was facilely obtained via a one-pot synthesis route, using （NH4）6Mo7O24 4H2O （AHM） as molybdenum sources and polymethylhydrosiloxane （PMHS） as silica sources at the initial synthetic step. The optimal C/Mo molar ratio in reaction system for complete carburization of molybdenum species was 7. The carburization process of molybdenum species followed a nontopotactic route involving a MoO2 intermediate phase, which was evidenced by XRD, N2 adsorption-desorption and in situ XPS. Formation mechanism of Mo-M-SiO2 precursor was also proposed by observation of the reaction between AHM and PMHS with TEM. Furthermore, by adding TEOS into silica sources and adjusting TEOS/PMHS mass ratio, crystal phase of molybdenum carbides transferred from β-Mo2C to α-MoC1-x, and SiO2 structure changed from microporous to micro/mesoporous. Catalytic performances of samples were tested using CO hydrogenation as a probe reaction. The supported molybdenum carbides exhibited high selectivity for higher alcohol synthesis compared with bulk β-Mo2C and α-MoC1-x.

Revisiting the single-step synthesis of quantum dots:The hidden ligand-promoted surface reaction channels

In this work,we revisited the single-step synthesis of CdE(E=S,Se,and Te)quantum dots(QDs).Powdered CdO and elemental chalcogen were directly used for heating-up synthesis.Firstly,the in situ dissolution of the solid precursors and related QD formation channels were preliminarily investigated.In general,QDs were generated from homogeneous reactions between dissolved cadmium and chalcogen precursors in bulk solution.We found that,during single-step synthesis,both the dissolution of CdO and selenium proceeded faster than their ex situ dissolution respectively.To explain this result,we proposed the existence of extra surface reaction channels for QD formation.That is,QDs could also be generated via on-surface reactions between the solid precursors and the dissolved counter precursors(as“ligands”).The happening of these extra surface reactions would increase the overall dissolution rate of CdO and selenium.Further,the circulation of oleic acid which is peculiar to such single-step synthesis should also partly account for the accelerated dissolution of CdO.Finally,by comparing with two-step synthesis using pre-dissolved CdO,we presented that such single-step synthesis was reliable in making uniform CdE QDs with good reproducibility.Our work reaffirmed the great potential of this single-step strategy in cost-effective synthesis of monodisperse QDs.Moreover,the ligand-promoted surface reaction channels would be applicable in solution-phase synthesis of metal chalcogenide nanocrystals from solid precursors.

Multiplexed micro RNA TG-FRET assay with isothermal and amplification-free single-step

Human genome encodes more than 2000 distinct micro RNAs(Micro RNA database:http://www.mirbase.org/),a class of single-strand noncoding RNAs with a short length of 19 to 25 nucleotides[1].They take part as regulatory factors in almost all biological processes from cell proliferation,differentiation to death.Since the alternation in the micro RNA expression level can be associated with a num-

Comparison of endoscopic stenting for malignant biliary obstruction: A single-center study

AIM: To evaluate the efficacy and safety of single-step endoscopic placement of self-expandable metallic stents(SEMS) for treatment of obstructive jaundice.METHODS: A retrospective study was performed among 90 patients who underwent transpapillary biliary metallic stent placement for malignant biliary obstruction(MBO) between April 2005 and October 2012. The diagnosis of primary disease and MBO was based on abdominal ultrasound, computed tomography, magnetic resonance imaging, endoscopic ultrasound, endoscopic retrograde cholangiopancreatography with brush cytology, biopsy, and/or a combination of these modalities. The type of SEMS(covered or non-covered, 8 mm or 10 mm in diameter) was determined by the endoscopist. Ninety patients were divided into two groups: group 1(49 patients) who underwent a singlestep SEMS placement and group 2(41 patients) who underwent a two-step SEMS placement. The technical success rate, complication rate, stent patency, and patient survival rate were compared between the groups. In addition, to identify the clinical prognostic factors associated with patient survival, the following variables were evaluated in Cox-regression analysis: gender, age, etiology of MBO(pancreatic cancer or nonpancreatic cancer), clinical stage(Ⅳb; with distant metastases or Ⅳa >; without distant metastases), chemotherapy(with or without), patency of the stent, and the use of single-step or two-step SEMS. RESULTS: Immediate technical success was achieved in 93.9%(46/49) in group 1 and in 95.1%(39/41) in group 2, with no significant difference(P = 1.0). Similarly, there was no difference in the complication rates between the groups(group 1, 4.1% and group 2, 4.9%; P = 0.62). Stent failure was observed in 10 cases in group 1(20.4%) and in 16 cases in group 2(39.0%). The patency of stent and patient survival revealed no difference between the two groups with Kaplan-Meier analysis, with a mean patency of 111 ± 17 d in group 1 and 137 ± 19 d in group 2(P = 0.91), and a mean survival of 178 ± 35 d in group 1 and 222 ± 23 d in group 2(P = 0.57). On the contrary, the number of days of hospitalization associated with first-time SEMS placement in group 1 was shorter when compared with that number in group 2(28 vs 39 d; P < 0.05). Multivariate analysis revealed that a clinical stage of Ⅳa >(P = 0.0055), chemotherapy(P = 0.0048), and no patency of the stent(P = 0.011) were independent prognostic factors associated with patient survival.CONCLUSION: Our results showed that single-step endoscopic metal stent placement was safe and effective for treating obstructive jaundice secondary to various inoperable malignancies.

A Novel Method for the Preparation of Octyl Bonded Styrene-divinylbenzene HPLC Packings

Monodisperse octyl bonded poly（styrene-divinylbenzene） （C8-PS-DVB） beads were prepared via a single-step swelling and polymerization method. Fourier transform infrared and chromatographic evaluation were used to confirm the reaction between the octene and divinylbenzene.

High-dielectric loss black silicon decorated with multi-nanostructure for wide-band mid-infrared absorption

Because of the excellent light-trapping ability of black silicon,it has emerged as a versatile substrate for photothermic applications.In this paper,multi-nanostructured black silicon with wide-band mid-infrared absorption properties for application in pyroelectric detectors is reported.Black silicon is fabricated on a substrate surface masked by Ag nanoparticle arrays using single-step etching of C_(4)F_(8)and SF_(6)plasma.The low absorption of black silicon in the mid-infrared region is improved when a secondary nanostructure with Pt nanoparticles and SiO_(2)thin films is deposited on the surface of the prepared black silicon by microelectromechanical system(MEMS)processes.Electrons are scattered at particle boundary,resulting in dielectric loss to incident infrared(IR)region.Compared to single black silicon,the structure decorated with the multi-nanostructure can achieve higher infrared absorption,which is contributed to the high-dielectric loss properties of the Pt nanoparticles.Simulations and experiments show that the thickness of black silicon and number of layers of platinum particles contribute to mid-infrared absorption,with wavelength ranging from 2.5 to 20.0μm,and the absorption reaches~90%.The proposed absorber provides a promising solution for thermal detectors.